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Title: The population biology of Charophytes in the context of shallow lake restoration
Author: Smith, David Charles.
ISNI:       0000 0001 3429 7082
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2003
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The charophytes comprise a group of green algae that is now recognised both for its evolutionary and ecological significance. Ecologically, the larger charophytes (charales) are important colonizers of the bottom sediments of lakes and slowly flowing rivers, where they can form dense monocultures or communities with a variety of submerged angiosperm species ('macrophytes'),but population changes in these plants are often difficult to predict High sediment shear strengths are associated with greater abundance of charophytes. Distribution of 00 spores through water movement is unlikely. Charophyte oospores will sink below the depth at which they are capable of emergence in sediments with very low shear strengths. Oospores will not germination in anoxic conditions, but oospores of Chara vulgaris will achieve germination in most other conditions. A method of showing viability in charophyte oospores, which eliminates the need for extensive germination trials is developed. Chara intermedia grows better at low light flux densities, but will not outcompete other macrophytes Re-growth from small fragments of charophyte stem is possible in sediments with low shear strength. These fragments respond to a range of planting methods, but this achievement is difficult to duplicate under field conditions. Charophyte growth rates are particularly sensitive to water temperature, and the process of gametangia formation depends on raised water temperatures. A model suggesting the charophyte population response to water temperatures, and length of growing season is presented. The actual response of charophyte populations to temperature fluctuations over a period of 18 years is examined. Antifouling paints contain substances that cause stress to charophytes. They also contain high concentrations of copper, enabling the use of sediment total copper content as an indicator of their past presence. Low biocide concentrations are shown to effect charophyte growth rates at typical spring temperatures, a time when competition with other macrophytes is particularly important.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available